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Demonstration creating a running process with a let-bound process-environment.
;;; NOTE: The process output from the gls command tends to be truncated when both
;;; (1) _not_ using a process filter and (2) _not_ using a pipe. When _not_ using a
;;; process filter, the workaround is to use a pipe by either setting the variable
;;; `process-connection-type' to `nil`; or, using the `make-process' keyword/argument
;;; pair of :connection-type 'pipe. Said workaround, however, has the disadvantage
;;; of having all the output arriving in one fell swoop and window-start of the
;;; process output buffer is point-max of the output -- meaning that the output is
;;; not visible unless using a command such as recenter on the output window buffer.
(defun gls-example (&optional dir)
"Demonstration creating a running process with a let-bound process-environment."
(interactive)
(let* ((directory (cond
(dir (directory-file-name dir))
(t
(directory-file-name default-directory))))
(default-directory directory)
(my-process-buffer (get-buffer-create "*GLS-BUFFER*"))
(my-process-filter
(lambda (proc string)
(let (point)
(with-current-buffer (process-buffer proc)
(insert string)
(setq point (point)))
(set-window-point (get-buffer-window (process-buffer proc)) point))))
(my-start-process
;;; This is a variation of `start-process' that modifies the
;;; process environment on a let-bound-basis
(lambda (name buffer program &rest program-args)
(unless (fboundp 'make-process)
(error "Emacs was compiled without subprocess support"))
(let* ((macports (concat user-emacs-directory ".0.macports/bin"))
(path (concat macports ":" (getenv "PATH")))
(temp (mapcar 'concat process-environment))
(newenv (setenv-internal temp "PATH" path t))
(process-environment newenv))
(apply #'make-process
(append (list :name name :buffer buffer)
(when program
(list :command (cons program program-args)))))))))
(display-buffer my-process-buffer t)
(with-current-buffer my-process-buffer
(setq truncate-lines t)
(erase-buffer))
(set-process-sentinel
(let ((proc (funcall my-start-process
"my-process-name"
my-process-buffer
"/bin/bash" "-c" "gls -la")))
(set-process-filter proc `(lambda (proc string)
(funcall ,my-process-filter proc string)))
proc)
(lambda (p e) (when (= 0 (process-exit-status p))
(message "Congratulations -- process executed normally!"))))))
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